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Scan signatures to work on any background color

Added on Thursday 22nd of June 2006 06:43 am EST

Application:

Adobe Photoshop 7/CS/CS2

Operating Systems:

Macintosh, Microsoft Windows

I need to scan in my boss’s signature for a letter I’m putting together in a page layout application. It’s going to be placed on a colored background so I need to remove the white background from the signature. I just can’t seem to eliminate all the white pixels, however. What’s the best way to scan it in, and is there an easy way to eliminate the white background?

When you scan a signature, your best bet is to scan it in as line art. The general rule for scanning line art is to scan at the resolution that your output device will print at. However, in higher-resolution devices, such as image setters, the resolution they can print at is much higher than you’ll need. Anything beyond 1200 ppi won’t gain your image any advantage; it will only increase the file size. Use Table A as a reference for the resolution to scan your line-art signature, depending on your output device.

Table A

Optimum resolutions for line art scans

Output device

Device resolution

Optimum scan resolution

Desktop inkjet printer

600 dpi

600 ppi

Desktop laser printer

720 dpi

720 ppi

High resolution laser printer

1200 dpi

800-1200 ppi

Imagesetter

1270-2540

800-1200 ppi

Save your image

When your scan is complete, don’t sweat over selections for this one. Simply leave the file as a bitmap and save it as a TIFF. If you scanned your image in as line art, the image should be a bitmap already. If you want to be sure your file is a bitmap, choose Image > Mode > Bitmap.

Note: If the Bitmap option is unavailable, you must first make the image Grayscale, and then make it a bitmap.

When you save the file as a bitmap TIFF, the white background is transparent when you bring it into InDesign or Quark, so you can place the signature on a colored background without the risk of any fringe. And while it looks gnarly and pixilated onscreen, the printout will be quite crisp, as shown in Figure A.

A

Tackle Pantone value mismatches with ease

by Amy Palermo

Application:

Adobe Photoshop 7/CS/CS2

Operating Systems:

Macintosh, Microsoft Windows

When I select a Pantone color from the Color Picker in Photoshop, the values often change after I’ve used them. For example, first I select Pantone Coated 312 and dump it into my file with the Paint Bucket, and then resample the color with the Eyedropper tool. When I go back to the Clor Picker, the Pantone has switched to 801C. Any clue what’s going on here?

Working with Pantones in Photoshop can be a little sticky. It isn’t as cut and dry as simply selecting a Pantone swatch and expecting accurate results. First and foremost, if you’re using a Pantone spot color in your Photoshop file for a print job, you either need to be in Duotone Mode, Multichannel Mode, or CMYK Mode with a spot channel in place. Otherwise, the color simply gets blended in with, or more accurately, separated amongst the channels in your document, and it isn’t a Pantone spot color anymore.